1. Field
This disclosure relates to positive active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery including the same.
2. Description of the Related Art
Rechargeable lithium batteries have recently drawn attention as a power source for small portable electronic devices. They use an organic electrolyte solution and thereby, have a discharge voltage that is at least two times higher than that of conventional batteries using an alkali aqueous solution, and as a result, they have relatively high energy density.
A rechargeable lithium battery is manufactured by injecting an electrolyte into an electrode assembly. The electrode assembly includes a positive electrode including a positive active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative active material capable of intercalating/deintercalating lithium ions.
As for the positive active material, LiCoO2 has been widely used, however, it has a high manufacturing cost and an unstable supply due to the scarcity of cobalt (Co). Accordingly, a positive active material including Ni (nickel) and/or Mn (manganese) has been developed.
The positive active material using Ni (nickel) may be appropriately used for a high-capacity and high voltage battery but has an unstable structure and thus, deteriorates capacity and in addition, reacts with an electrolyte and thus, it has low thermal stability.
On the other hand over lithiated oxides (which may include Mn oxides) release lithium ions at a voltage of greater than or equal to about 4.55 V and thus, they have an increased capacity. However, the over lithiated oxides generate oxygen gas during the reaction and also, have a reduced initial efficiency because the lithium ions released from an irreversible reaction do not reparticipate in the reaction.